Risk Factors for Delayed Resorption of Costal Cartilage Framework Following Microtia Reconstruction

Background: Resorption of the cartilage framework results from hematoma or infection, deteriorating outcomes in microtia reconstruction. Delayed resorption still occurs for unclear reasons in patients without adverse events. The risk factors for delayed framework resorption were explored in this 20-year microtia cohort. Methods: Patients who underwent auricular elevation >5 years ago were reviewed from January 2001 to March 2019. Bilateral microtia, infection, and hematoma cases were excluded. Framework resorption was graded on the last photographs as none to minimal (grade 1), blunted but all components present (grade 2), loss of either the helical or antihelical component (grade 3), and loss of all components (grade 4). Logistic regression was used to evaluate independent risk factors for grade 3 and 4 resorption. Results: Of the 367 patients, 132 revisited our institution with a mean postoperative duration of 8.0 years. Grade 1 resorption was seen in 37.1%, 2 in 31.8%, 3 in 24.2%, and 4 in 6.8%. Canalplasty increased the risk of resorption regardless of timing (before auricular elevation, p = 0.017; after auricular elevation, p = 0.011). Body mass index at the time of cartilage harvest lowered the risk of resorption (p = 0.057) with clinical significance. Conclusions: Canalplasty may be avoided given the risk of framework resorption or may be performed with antiresorption strategies if the expected hearing outcome is superior. Our timing of harvest at the age of 10 years may have ensured cartilage maturation, both in terms of size and biomechanics, resulting in the resistance to resorption.